Eastern Europe's rapidly-escalating HIV epidemic has been driven by widescale cultural, social, and economic transformations following the sudden collapse of the former Soviet Union. Drug use and commercial sex (once uncommon in the region) are now widespread. The HIV epidemic in Russia, first associated with injection drug use, is now undergoing an epidemiological transition to predominantly sexual transmission. To forestall the emergence of a widescale sexual epidemic, it is essential to stimulate social and behavioral science research to guide the development of improved HIV prevention interventions culturally appropriate for the region. Prevention efforts carefully grounded in social sciences is especially critical because Russia's HIV epidemic is so closely intertwined with rapidly-changing social, cultural, and behavioral values. This application proposes to establish the Interdisciplinary Center for AIDS Research and Training (ICART) at Botkin Hospital for Infectious Diseases in St. Petersburg, Russia-the largest medical HIV care provider in northwestern Russia and the central hub for many HIV/AIDS prevention and care NGOs. ICART will consist of a consortium in Russia that is led by Botkin Hospital, and includes participation by the St. Petersburg Center for Independent Sociological Research, Faculty of Economics at Moscow State University, Pasteur Institute in St. Petersburg, St. Petersburg State Medical Pediatric Academy, and an NGO active in community HIV/AIDS prevention and care, "Doctors to Children." ICART will also partner with senior investigators at the Center for AIDS Intervention Research (CAIR) at the Medical College of Wisconsin. CAIR, an NIMH-funded P30 HIV prevention research Center since 1994, has undertaken successful HIV prevention studies in the region, collaborating with many of the investigators who will be affiliated with ICART. ICART's thematic research mission will be the theoretical conceptualization, conduct, and evaluation of HIV primary prevention interventions carried out with vulnerable community populations;the conduct of behavioral and social science research related to needs of HIV-infected persons, including research on stigma, treatment adherence, psychosocial coping with HIV, and prevention of HIV transmission from infected to uninfected persons;and qualitative and quantitative basic social science research necessary for the development of effective, culturally-tailored HIV primary and secondary prevention interventions.